Polycarboxylamides from 1, 2-bis (aminomethyl) cyclobutane



United States Patent 3 288 760 POLYCARBOXYLAMIDES, FROM 1,2-BIS(AMINO- METHYL)CYCLOBUTANE Ralph Courtenay Schreyer, Wilmington, Del., assignor to No. 97,454. Divided and this application Nov. 20, 1963, Ser. No. 325,136

11 Claims. (Cl. 26078) This invention relates to a novel class of polycarboxylamides made by the polymerization of trans-1,2-bis- (aminomethyl)cyclobutane with dicarboxylic acids.

This application is a division of my copending application Serial Number 97,454, filed March 22, 1961, now United States Patent 3,192,262, issued June 29, 1965.

It is an object of this invention to provide a novel class of nylon resins made by the condensation polymerization of trans-1,2-bis(aminomethyl)cyclobutane with dicarboxylic acids. Other objects and advantages of this invention will appear hereinafter.

It has been discovered, as set forth in my United States Patent 3,192,262, supra, that 1,2-dicyanocyclobutane can be hydrogenated in the presence of ammonia and in the liquid phase, under at least about 100 atmospheres of hydrogen, and preferably under from about 400 to about 1000 atmospheres of hydrogen, over a hydrogenation catalyst, comprising a transition metal of Group VIII of the Periodic Table of Elements, and at a temperature in the range of 75 to 250 C. to give trans-l,2-bis(aminomethyl)cyclobutane and 3-aza(3.2.0)bicycloheptane.

It has also been discovered, as set forth in my United States Patent 3,192,262, supra, that the preferred conditions for the preparation of trans-1,2-bis(aminomethyl)- cyclobutane in high yield require the use of trans-1,2-dicyanocyclobutane as the starting material with the hydrogenation being carried out at as low a temperature as will give an economic rate of reaction, usually a temperature in the range of 75 to about 150 C.

In accord with the object of this invention, it has been found that trans-1,2-bis(aminomethyl)cyclobutane can be converted into a series of novel and useful polycarboxylamides by polymerization with dicarboxylic acids or their amide-forming derivatives.

The starting material, 1,2-dicyanocyclobutane, can be prepared by a process which involves the thermal dimerization of acrylonitrile. This preparation was first described by Coyner and Hillman, J. Amer. Chem. Soc., 71, p. 324 (1949). However, the conditions of reaction described by Coyner and Hillman resulted in considerable loss to tarry, resinous polymeric byproducts. A much improved process for the dimerization of acrylonitrile to 1,2-dicyanocyclobutane is described in an application, Serial Number 857,557, filed December 7, 1959,- by William L. Lehn and George R. Nacci, now abandoned.

It is known that these processes for the dimerization of acrylonitrile yield a mixture of the cisand trans-geometric isomers of 1,2-dicyanocyclobutane. These isomers can be separated by fractional distillation into two fractions which, after recrysallization, have boiling points, under 6 mm. pressure, of 123 C. and 165 C., respectively.

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Both pure isomers are solids; after recrystallization from ether-ethanol, the melting point of the lower-boiling isomer is 37-38 C. and the melting point of the higher boiling isomer is 72-73" C. According to the rule of Von AuWers-Skita (see Steric Effects in Organic Chemistry, ed. M. S. Newman, page 20, John Wiley & Sons, Inc., New York), the higher boiling and higher melting isomer should have the cis-configuration. The assignment was confirmed by measurement of the dipole moments: the dipole moment of the low-melting isomer (trans-form) is 4.3 Debyes and the dipole moment of the high-melting isomer (cis-form) is 6.0 Debyes.

Since the preferred process for the production of trans- 1,2-bis(aminomethyl)cyclobutane requires the use of trans-1,2-dicyanocyclobutane as the starting material, an aspect of the present invention is the discovery of a process for converting cis-1,2-dicyanocyclobutane to trans-1,2- dicyanocyclobutane. In accord with this aspect of the invention, it has been discovered that nickel or cobalt hydrogenation catalysts will isomerize the cis-isomer to the trans-isomer at temperatures in the range of about to 350 C. While isomerization does occur in the liquid phase under these conditions, it is preferable for high con version and recovery to employ a vapor phase isomerization step at 250 to 350 C. A mixture consisting of the cisand trans-isomeric 1,2-dicyan0cyclobutanes, usually with the cis-isomer present in at least 50%, is vaporized and passed continuously over a bed of a cobalt or nickel hydrogenation catalyst at a temperature in the range of 150 to 350 C., preferably in the range of 250 to 350 C. in this vapor phase process. The effluent is separated into the cisand trans-isomers by fractional distillation, and the trans-isomer is then hydrogenated in the liquid phase in accordance with the process of this invention while the cis-isomer is recirculated to the vapor phase isomerization step.

Hydrogenation catalysts which have been found operable for the conversion of 1,2-dicyanocyclobutane to trans-1,2-bis(aminomethyl)cyclobutane comprise Raney nickel and Raney cobalt, and the reduced oxides of the transition elements of Group VIII of the Periodic Table. Cobalt and nickel are the preferred catalysts since they are particularly effective in isomerizing cis-1,2-dicyanobutanes to the trans-isomers. These catalysts may be supported on silica, alumina, or carbon, or they may be prepared by reduction of the pure metal oxides or salts. Whether supported or unsupported, these Group VIII reduced metal catalysts are activated by hydrogenation prior to use. Also effective are the molybdites with Group VIII metal cations, particularly cobalt or nickel molybdite.

While, as indicated hereinabove, the preferred process for the production of trans-l,2-bis(aminomethyl)cyclobutane employs the trans-1,Z-dicyanocyclobutaue is-omer as starting material, the mixture of isomers as obtained from the dimerization of acrylonitrile is also suit- When the mixture is employed, there is obtained as a by-product a novel secondary amine, 3-aza(3.2.0)bicycloheptane; no evidence is found for the presence of any of the theoretically-possible cis-1,2-(aminomethyl)cyclobutane, so it is believed that this isomer is completely converted to 3-aza(3.2.0)bicycl-oheptane under the conditions of the reaction.

It is essential that no molecular hydrogen be present Therefore, the reactions occurring in the process of trans-l,2-bis(ammomet-hyl)cyclobutane boiled at 50-65 this invention can be-indicated-by the following equations: C./1 mm. Hg. This was refined by atmospheric pres- OHz-COEN cat. CH2COH2-NH2 i l H2 i OH2-('IJH NH; CHzCH GEN GHzNHz trans-1,2- trans-1,2-bis (aminodicyanocyclobutane methyl) cyclobutane Co or H NH H l Ni oat. i I OH2CC- OH2COEN NH CH2OCH2NH2 HzCC H2 H 1 i eat. CHrO-CEN I'Iz +Hz NH CH2GCEN H H H q I CH2COHz cis-1,2-d1cyanocyelobutane CHzCC-H2NH2 i NH NH CH2CC H2-NH2 Ii]: CHE-(f-Cflg B-aza-(3.2.0)-bycycloheptaue It is not certain by which route 3-aza(3.2.0)bicyclohepsure distillation in a three-foot, platinum, spinning-band tane is formed, so alternative routes are indicated in the column yielding 8 parts of. center cut having a boiling equations. 7 point of l93193.5 Q/atmospheric pressure;

It has been found that when the liquid phase hydrogenation of mixtures of cisand trans-1,2-dicyanobutane is carried out in the Presence of 0013311 or nickel 3 This product was subjected to elemental analysis and alyst, the PIOP It I 0f diamifle icy SCCOIldaTY to determination of its neutral equivalent with the folamine obtained may be greater than would be predicted lowing r sults; from the proportion of trans-isomer in the starting matenal- 7 Calculated Found Therefore, some isomerizatron does occur in the liquid 40 phase under these conditions. In view of this, it is sur- Percent 631 63,86

Percent H 12.29 12.30;12.55 prising that ad1pon1tr1le is not a mayor product under PemntN M56 2441361114 these conditions since, as disclosed in my application NeutralEqfln 57 56;,5

Serial Number 36,702, filed June 17, 1960, now United States Patent Number 3,092,654, patented June 4, 1963,

A re etition of the above ex eriment in which the Rane similar catalysts convert 1,2-d1cyanocyclobutanes exp p y nickel catalyst was replaced -by a Raney cobalt catalyst clusively to adiponitrile when hydrogenation is carried gave substantially equivalent Products out in the vapor phase; under those conditions, ring scission and hydrogenation of the resulting free radi- EXAMPLE 2 cals occur preferentially to reduction of the nitrile groups. Thimpfive3 parts of 1 zdicyanocyclobutane which The following examples are provided to illustrate prepfined at 124.50 to 2 0/9 mm Hg, 85 of aration of the diamine employed in the polyamides of the hydrous ammonia and 5 parts of 5% ruthenium on Invention In these examples parts are by welght unless charcoal catalyst were charged to a steel shaker tube otherwise indicawd: and processed for one hour at 225 C. under hydrogen EXAMPLE 1 at a pressure of 700 atmospheres. The reaction products were separated by distillation, as in Example 1. How- Thirty parts of a mixture consisting of the cru ever, in the instant example, the conversion to diamine aerylonitrile dimer obtained from thermal dimerization was 103 parts d th conversion t 3- (3 2 0),bi 1 of acryloni-trile (a mixture of cis-l,2-dicyan0cycl0butane heptane was 7.9 parts. The latter product was char-. d trans-Ll-dicyanocvclobutane wmaining PP acterized, after refractionation; it had a boiling point of mat ly 40% cis-isomer and 60% trans-isomer), 85 Parts 127130 C. at atmospheric pressure; 1 =l.4530. anhydrous ammonia, and 5 parts of a Raney nickel Cat- Elemental analysis and determination of the neutral alyst were charged a high-Pressure $1661 Shaker 111116 equivalent of this bicyclic secondary amine gave the foland processed for one hour at 150 C. under hydrogen lowing results: at a pressure of 600 atmospheres.

The shaker tube was cooled, the pressure vented, and Calculated Found the contents discharged, the tube was rinsed with methanol. Catalyst was removed by filtration. The product Percent 743 72 0;7l 6 mixture comprised .trans-1,2-bis(arninomethyl)cyclobugercefltH 1133 5 tane, and 3-aza(3.2.0)bicycloheptane, together with iifgi g1, ifi fi fig' methanol wash. The latter was separated by distillation. The reaction products were separated by crude fractional distillation at 1 mm. pressure, and 17 parts EXAMPLE3 of the crude diamine was obtained as well as a frac- One hundred and twenty parts of a mixture of cisand tion comprising 3-aza(3.2.0)bicycloheptane. The crude 75 trans-1,2-dicyanocycl0butane isomers, 255 parts anhydrous NH and 44 parts Raney nickel catalyst were charged to a stainless steel agitated autoclave and processed for one hour at 150 C. under 500 atmospheres of hydrogen pressure. The pressure was vented and the contents of the autoclave rinsed out with 175 cc. of 5 by distillation to separate a center cut from foreshots and heel.

The center cut, 91.7 parts, was charged to the stillpot under a spinning band column and fractionated by distillation at atmospheric pressure. The results of this Cut 2 was analyzed as the center cut consisting of pure 3-aza(3.2.0)bicycloheptane and Cut 5 was analyzed as the center cut consisting of pure trans-1,2-bis(aminomethyl) cyc-lobutane,

C UT 2 [3-AZA(3.2.0)BICYOLOHEPTANE] Calculated Found Percent G 74.3 74.7; 74.3 Percent H 11.33 11.9;1115 Percent N 14.4 14.13; 14.20 Neutral Eq 97 98: 99

The infra-red spectrum of Cut 2 showed a band at 305 characteristic of a single N-H bond as required by the assigned structure.

OUT 5 (TRANS-LfZ-BIS(AMINOMETHYL) CYCLOBUTANE Calculated Found Percent (3.- 63.1 62 .7; 62.7 Percent PL- 12.29 12.3; 12 .6 Percent N 24.56 24.10: 24.24 Neutral Eq 57 57 The infrared spectrum of Cut 5 Was measured and found to be consistent with the assigned structure: two NH stretching bands in the 3p. region; a NH deformation band at 6.2 1., and broad diamine absorption in the 12 region.

EXAMPLE 4 A catalyst was prepared by reducing 50 cc. of cobalt oxide in a reaction tube by passing hydrogen at 300 C. over it for several hours. The hydrogen was displaced with nitrogen. Then a feed consisting of 72% cisand 28% trans-1,Z-dicyanocyclobutane was vaporized and passed through the tube with N gas as carrier at a rate to give about 5 seconds contact time. Three temperature ranges were tried. The efiiuent was condensed and subsequently analyzed by gas chromatography. Results are shown in Table B. 75

Table B ISOME RIZATION OF 018- TO TRANS-1,2-DICYANOCYCLO- BUTANE Percent Percent Percent Percent Temp., C. cc./N Ree. Trans- Cis- Low Boilers Similar results were achieved in another experiment with a reduced nickel oxide catalyst.

EXAMPLE 5 A stirred, stainless steel autoclave equipped for continuous addition and removal of liquid was charged with a cobalt catalyst prepared as described in Example 4 and with trans-1,2-dicyanocyclobutane prepared as described in Example 4. The autoclave was pressured to 60 0 atmospheres with hydrogen and the contents stirred and heated to, and maintained at, to C. Trans- 1,2-dicyanocyclobutane and a large excess of ammonia were continuously added and product stream removed at such a rate as to provide a 30-minute average contact time.

The liquid efiiuent was separated by fractional distillation to recover the lower-boiling fraction, and the higherboiling residue, unreacted trans-1,2-dicyanocyclobntane was recycled to the autoclave. The lower boiling fraction consisted essentially of only trans-1,2-bis(ar nino methyl)cyclobutane which was further refined by distillation.

In another experiment, similar results were achieved using a reduced nickel oxide catalyst for the hydrogenation.

The novel polyamides with which this invention is concerned are fiber-forming, synthetic polycarboxylamides in which the carboxylamide linkages form an integral part of the polymer chains and which, upon hydrolysis, yield trans-1, 2-bis(aminomethyl)cyclobutane, and at least one dicarboxylic acid selected from the group consisting of aromatic dicarboxylic acids and linearaliphatic dicarboxylic acids having from two to twelve carbon atoms in the molecule.

The polyamides of this invention can be prepared by polymerization of salts prepared by reaction of equivalent proportions of diamine and dicarboxylic acid. In a typical procedure, solutions of equivalent amounts of diamine and of dicarboxylic acid in a polar organic solvent for the monomers, such as ethanol, are mixed and the resultant, crystalline salt which precipitates is heated in an autoclave in an inert atmosphere under autogeneous pressure at a temperature in the range of 220 to 300 C until polymerization under these conditions is substantially complete (about one to three hours), then, to complete the polymerization, the autoclave is evacuated and the heating continued under reduced pressure with a nitrogen bleed until the evolution of water substantially ceases. Another, alternative procedure which can be employed is to react the diamine with an amide-forming derivative of the dicarboxylic acid, such as an acid chloride. Where acid chlorides are employed, it is preferable to add a base to neutralize the evolved HCl. A conven- 5 ient process employing acid chlorides involves interfacial polymerization in which the acid chloride, dissolved in a water-immiscible solvent, is dispersed in an aqueous medium to which the diamine and sodium hydroxide are added in equivalent proportions.

Aromatic dicarboxylic acids which can be employed for the preparation of the polyamides of this invention include terephthalic acid, isophthalic acid, 4,4-dicarboxydiphenyl ether, diphenic acid and naphthalic acid. Aliphatic dicarboxylic acids which can be employed for'the preparation of the p-olyamide of this invention include oxalic acid, adipic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid.

For certain purposes, particularly for the preparation of polyamides for melt-spinning, it has been found that the polymerization of trans-l,2-bis(aminomethyl)cyclobutane with a mixture of dicarboxylic acids consisting of an aromatic dicarboxylic acid and a linear aliphatic dicarboxylic acid provides particularly valuable polyamides. By varying the proportion of aromatic to aliphatic dicarboxylic acid, polyarnides having any desired melting point intermediatebetween the melting points of the polyamides obtained with either dicarboxylic acid alone, can be obtained.

The polycarboxylamides of this invention are useful for the preparation of textile fibers, both monofilaments and yarns. They can be employed as molding granules for the fabrication of shaped articles by extrusion and by injection molding. Fibers, tubing, and pipe are examples of useful articles which can be made by extrusion of these polya-mides. Gears, housings, containers, door han- H dles and the like can be made from these polyarnides by injection molding. These polyamides are more transparent than many of the nylons previously known to commerce, making them unique in applications where transparency is desired, particularly in films and containers. Because of their optical properties, they can be pigmented or dyed to provide brilliant colored plastic articles.

The following examples of the preparation and evaluation of the polycarboxylamides of this invention are provided as illustrations of this aspect of this invention Without any intention to limit the invention to the specific illustions:

EXAMPLE 6 As an example of the preparation of a nylon from trans-1,2-bis(aminomethyl)cyclobutane, a salt was struck, in ethanol, between equivalent amounts of trans-1,2-bis- (aminomethyl)cyclobutane and pure adipic acid. A quan titative yield of the crystalline salt was obtained; this salt had a melting point of 197199 C. This salt was sealed in a glass tube under N atmosphere and heated for 2 hours at 245 C. under autogeneous pressure. The prepolymer obtained was colorless; it was further polymerized by heating at 225 C. under a vacuum with N bleed to carry off evolved water. The final polyamide was transparent. It had a softening point of 85 90 C. and had a high molecular weight, as judged from its solution viscosity in metacresol (11 1.3). This nylon is a tough plastic for use in low temperature applications and as a nylon for either solution or dispersion coating of fabric substrates, paper, and the like.

EXAMPLE 7 As another example of the preparation of a nylon polymer from the novel diamine of this invention, an interfacial polymerization was carried out. A mixture of 150 ml. H O, 0.5 g. sodium lauryl sulfate (as dispersing agent), 50 ml. toluene, and 10.15 g. isophthaloyl chloride was vigorously stirred to give a dispersion of the organic phase in the aqueous phase. There was then added all at once a mixture of 75 ml. H O, 4.2 NaOH, and 5.7 g. trans-1,2-bis(aminomethyl)cyclobutane. The temperature rose to about 70 C., and a solid polycarboxylamide was precipitated. This polyamide was collected by filtration, washed with 10% aqueous NaOH and twice with water. After drying overnight in a vacuum oven at 100 C., the yield of polymer was found to be 9.6 g.; M.P.=200220 C.; 1 :0] (metacresol). This highmelting nylon is particularly useful in the preparation of yarns and filaments with unique properties including high modulus which makes it a valuable fiber for crease-resistant, wash-and-wear textiles.

EXAMPLE 8 A salt was struck, following procedure of Example 6, between equivalent amounts of trans-l,2-bis(aminomethyl)cyclobutane and pure sebacic acid. The crystalline salt was isolated and heated, under autogenous pressure, in a sealed reactor at 250 C. for two hours. The pressure was released and a N bleed passed through the melt for /2 hour at a temperature of 283 C. The polymerization was completed by heating under vacuum at 283 C. for /2 hour. The resultant polymer, on cooling, was a tough, white solid plastic. Its inherent viscosity, measured at 25 C. in metacresol at a concentra tion of 0.5 g./ 100 ml. solvent, was 0.74. This polymer had a melt temperature of 170 C. and a stick temperature of 143 C. The melt temperature was determined as the lowest temperature at which a small pellet melted when placed on a preheated block; the temperature was raised in increments of 25 C. until the temperature was reached at which a solid pellet rapidly liquified upon contact. The stick temperature was determined by touching a piece of solid polymer to a heated block; the temperature at which the polymer would stick and then could be pulled out to a fine filament was taken as the stick temperature.

EXAMPLE 9 A salt was struck, following the procedure of Example 6, between equivalent amounts of trans-1,2-his(aminomethyl)cyclobutane and pure terephthalic acid. The crystalline salt was isolated and heated, under autogenous pressure, in a sealed reactor at 295 C. for one hour. The pressure was released and a N bleed passed over the prepolymer for one hour at a temperature of 295 C. The polymerization was completed by heating under vacuum at 295 C. for one hour. The resultant polyamide was extremely high melting, having a melt temperature higher than 350 C. This polymer was insoluble in metacresol but had an inherent viscosity of 0.40 at 25 C. when determined in sulfuric acid at a concentration of 0.5 g./ ml. of solvent.

EXAMPLE 10 A prepolymer was prepared by refluxing a mixture of trans-l,2-bis(aminomethyl)cyclobutane with excess di-nbutyloxylate. A solid prepolymer (low molecular weight polyamide) precipitated and was isolated. This solid prepolymer in the form of a powder was heated in a tubular reactor with N passing through at 283 C. for 2% hours. The resultant polyarnide had a melt temperature of 337 C. and an inherent viscosity of 0.35, determined in concentrated sulfuric acid at 25 C. at a concentration of 0.5 g./ 100 ml. solvent. This polyoxamide was insoluble in metacresol.

I claim:

1 A fiber-forming, synthetic polycarboxylamide in which the carboxylamide linkages form an integral part of the polymer chains, of trans-l,2-bis(aminomethyl)- cyclobutane and at least one dicarboxylic acid selected from the group consisting of aromatic dicarboxylic acids and linear aliphatic dicarboxylic acids having from two to twelve carbon atoms in the molecule.

2. A polycarboxylamide of claim 1 in the form of a monofilament.

3. A polycarboxylamide of claim 1 in the form of a textile yarn.

4. A polycarboxylamide of claim 1 in the form of a hollow tube.

5. A fiber-forming, synthetic polycarboxylamide of claim 1, in which the carboxylamide linkages from an integral part of the polymer chains of trans-l,2-bis(aminomethyl)cyclobutane and adipic acid.

6. A fiber-forming, synthetic polycarboxylamide of claim 1, in which the carboxylamide linkages form an integral part of the polymer chains, of trans-1,2-bis- (aminomethyl)cyclobutane and terephthalic acid.

7. A fiber-forming, synthetic polycarboxylamide of claim 1, in which the carboxylamide linkages form an integral part of the polymer chains, of trans-1,2-bis(amino- Inethyl)cyclobutane and isophthalic acid.

8. A fiber-forming, synthetic polycarboxylamide of claim 1, in which the carboxylamide linkages form an integral part of the polymer chains, of trans-1,2-bis- (aminomethyl)cyclobutane, an aromatic dicarboxylic acid, and a linear aliphatic dicarboxylic acid having from two to twelve carbon atoms in the molecule.

9. A polycarboxylamide of claim 8 in which the aromatic dicarboxylic acid is terephthalic acid and the aliphatic dicarboxylic acid is adipic acid.

10. A fiber-forming, synthetic polycarboxylamide of claim 1, in which the carboxylamide linkages form an integral part of the polymer chains, of trans-1,2-bis- (aminomethyl)cyclobutane and oxalic acid.

11. A fiber-forming, synthetic polycarboxylamide of claim 1, in which the carboxylamide linkages form an integral part of the polymer chains of trans-1,2-bis(aminomethyl)cyclobutane and dodecanedioic acid.

References Cited by the Examiner UNITED STATES PATENTS 2,130,948 9/1938 Carothers 26078 3,017,395 1/1962 Elam et al. 26078 3,074,914 1/1963 Armen 26078 OTHER REFERENCES WILLIAM H. SHORT, Primary Examiner.

LOUISE P. QUAST, Examiner.

H. D. ANDERSON, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,288,760 November 29, 1966 Ralph Courtenay Schreye'r It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 7, line 60, after "4.2" insert g. column 8, line 65, for "from" read form Signed and sealed this 11th day of March 1969.

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test:

ward M. Fletcher, Ir. EDWARD J. BRENNER testing Officer Commissioner of Patents 

1. A FIBER-FORMING, SYNTHETIC POLYCARBOXYLAMIDE IN WHICH THE CARBOXYLAMIDE LINKAGES FORM AN INTEGRAL PART OF THE POLYMER CHAINS, OF TRANS-1,2-BIS(AMINOMETHYL)CYCLOBUTANE AND AT LEAST ONE DICARBOXYLIC ACID SELECTED FROM THE GROUP CONSISTING OF AROMATIC DICABOXYLIC ACIDS AND LINEAR ALIPHATIC DICARBOXYLIC ACIDS HAVING FROM TWO TO TWELVE CARBON ATOMS IN THE MOLECULE. 